/*@ n>=0
 */
int sum (int n)
{
  int s;
  if (n==0)
    return 0;
  else {
    s = sum(n-1);
    s = s + n;
    return s;
  }
}
/*@  result == n*(n+1)/2
 */


/*@ */
void main()
{
  int x;
  x = sum (100);
  print(x);
  return;
}
/*@ */
